1. Field of the Disclosure
The disclosure relates to siloxane-based compositions, and more particular to a process of preparing siloxane-base compositions to form intermediate temperature plastic-like materials (from room temperature to 500° C.) and the use of the same as precursors polymers to form high temperature ceramics upon curing and glasses upon pyrolysis.
2. Related Art
In the current state of the art, siloxane-based compositions are used to prepare pre-ceramic polymer compositions, which are used as precursor resins in the preparation of ceramics and glasses. Most precursor resins may be categorized under one of two categories. Category one primarily includes silicone-like siloxanes, for example, methylsiloxanes. Category two primarily includes siloxanes with silicon-hydrogen (Si—H) bond coupled to either a carbon-carbon double (C═C) bond or a carbon-carbon triple (C≡C) bond of an organic compound. While these precursor resins produce good high temperature ceramic materials, they fall short in a number of areas as precursors.
For example, methysiloxanes as precursor resins under category one need to be pyrolyzed to form resins with desirable properties before they can be used in the preparation of ceramics or glasses. Methylsiloxanes, which are usually solids, require a solvent before they can be used in the preparation of pre-ceramic polymers. This presents an additional process step of dissolving the methylsiloxanes in an appropriate solvent in the preparation process. In addition, methylsiloxanes produce low strength, low modulus materials with poor tear strength when cured below pyrolysis temperatures.
Category two precursor resins, for example, resins with an empirical formula, SiCxOy, require relatively expensive starting materials. Starting materials with C═C bond, for example, divinyl benzene, dicyclopentadiene and butadiene may be hazardous to the environment. In addition, the use of these starting materials results in precursor resins, which require careful storage to ensure a stable shelf-life adding to storage costs. A further limitation of using such starting materials is having these starting materials as residue in any preparation process, which prevents the use of the materials in an open production environment.
In addition, category two precursor resins are limited in the extent to which modifications of their composition may be made. This restricts their application to being, at best, ceramic-forming polymers only.
Siloxane-based compositions may be used to produce UV curable resins for coating papers. Some precursor resins may be formulated in such a way as to produce stable glasses when pyrolyzed at high temperature where the final ceramic is devoid of carbon-oxygen (C—O) bonds.
Siloxane oligomers may be used as coupling agents, adhesion promoters, and adhesives in filled and unfilled organic polymers as wire and cable coatings and adhesives.